1. An in vitro slice preparation of rat cerebellar cortex was used to analyse long-lasting modifications of synaptic transmission at parallel fibre (PF)-Purkinje cell (PC) synapses. These use-dependent changes were induced by pairing PF-mediated EPSPs evoked at low frequency (1 Hz) with different levels of membrane polarization (or bioelectrical activities) of PCs for 15 min. 2. Experiments wer...

fertilization is triggered by changes in intracellular calcium concentration. in mammals, these transients in ooplasmic calcium concentration take the form of repetitive spikes, so called calcium oscillations (ca2+-oscillations). these oscillations are important for relieve of meiotic arrest and to induce all the other events of oocyte activation. although a surface mediated way of oocyte activ...

Cyclic ADP-ribose (cADPR) is a potentially important intracellular Ca2+ releasing messenger [1-5]. In pancreatic acinar cells where intracellular infusion of both inositol trisphosphate (IP3) and cADPR evoke repetitive Ca2+ spiking [6], the cADPR antagonist 8-NH2-cADPR [7], which blocks cADPR-evoked but not IP3-evoked Ca2+ spiking, can abolish Ca2+ spiking induced by physiological levels of the...

Synchronous neuronal firing can be induced in hippocampal slices in the absence of synaptic transmission by lowering extracellular Ca2+ and raising extracellular K+. However, the ionic mechanisms underlying this nonsynaptic synchronous firing are not well understood. In this study we have investigated the role of KCNQ/Kv7 channels in regulating this form of nonsynaptic bursting activity. Incuba...

Catecholamines participate in the pathogenesis of portal hypertension and liver fibrosis through alpha1-adrenoceptors. However, the underlying cellular and molecular mechanisms are largely unknown. Here, we investigated the effects of norepinephrine (NE) on human hepatic stellate cells (HSC), which exert vasoactive, inflammatory, and fibrogenic actions in the injured liver. Adrenoceptor express...

The endogenously bursting pacemaker neuron R15 of Aplysia exhibits an inwardly rectifying K+ current (IR) that was shown previously to be enhanced by various neurotransmitters via the intracellular second messenger, cyclic AMP (Drummond et al., 1980; Benson and Levitan, 1983; Levitan et al., 1987). Here we present evidence that Ca2+ influx, either caused by spontaneous bursting activity or elic...

In a previous study iontophoresis of glutamate on the apical dendrite of layer 5 pyramidal neurons from rat neocortex was used to identify sites at which dendritic depolarization evoked small, prolonged Ca2+ spikes and/or low-threshold Na+ spikes recorded by an intracellular microelectrode in the soma. These spikes were identified as originating in the dendrite. Here we evoke similar dendritic ...

Intracellular free calcium concentration ([Ca2+]i) was measured in fura-2-loaded single rat mesangial cells by dual wavelength spectrofluorometry. Stimulation with arginine vasopressin (AVP) caused an initial sharp rise of [Ca2+]i followed by repetitive spikes. The frequency of the oscillations was dependent on the concentration of AVP. At 0.1, 1.0, 10.0, and 100.0 nM AVP, the frequencies of os...

In polarized epithelial cells, agonists trigger Ca2+ waves and oscillations. These patterns may be caused by the compartmentalization of inositol 1,4,5-trisphosphate (IP3)-sensitive Ca2+ pools into specific regions. We have investigated the relationship between the distribution of IP3 receptors (IP3Rs) and the spatiotemporal pattern of Ca2+ signaling in the duct cells of the rat submandibular g...